1. Field of the Invention
This invention relates to cyanoacrylate tissue adhesives, and more particularly, to bioabsorbable cyanoacrylate tissue adhesive compositions and to methods for making and using these compositions. The compositions are useful in medical applications, including, but not limited to, wound and surgical incision closure, medical device fixation, sealants and void fillers, embolic agents and other general medical applications.
2. Description of the Background
Surgical incisions and wounds may be closed by three general methods, suturing, stapling and adhesive bonding.
U.S. Pat. No. 5,578,046 notes that sutures are bioabsorbable when the material that they are made from is capable of being broken down into smaller constituents, which can be metabolized and excreted by the living organism. Such materials are useful for temporarily holding tissues in a desired position during healing and are absorbed by the organism after a period of time. U.S. Pat. No. 5,578,046 as well as the patents and literature in turn referenced by U.S. Pat. No. 5,578,046 are incorporated herein by reference.
Wound suturing has the advantage of producing bioabsorbable, non-toxic degradation products. However, it also has disadvantages. Suturing requires time and skill. It causes additional trauma to the tissue by piercing and does not provide a hermetic closure.
Cyanoacrylates posses the unique property to bond living tissue. They have been widely and successfully tested for closing wounds and incisions, especially in cases where suturing does not provide satisfactory results. See Lijoi A. et al, "Subacute left ventricular free wall rupture complicating acute myocardial infarction. Successful surgical repair with a sutureless technique", J. Cardiovascular Surgery, 1996 December, 37(6), 627-630; Tebala G. D. et al, "The use of cyanoacrylate tissue adhesive in high-risk intestinal anastomoses", Surgery Today, 1995, 25 (12), 1069-72 and Zaki I. et al, "Split skin grafting on severely damaged skin. A technique using absorbable tissue adhesive", J. of Dermatologic Surgery and Oncology, 1994 December, 20(12), 827-9.
Cyanoacrylate tissue adhesives have the following advantages over suturing: they save time; they can bond difficult to suture tissues; they can provide a hermetic closure; they have hemostatic action; they produce better cosmetic results; and they may be indispensable in emergencies.
A major disadvantage of cyanoacrylate adhesives is that one of the degradation products is formaldehyde, which is toxic to the surrounding tissues (see Pani K. C. et al, "The degradation of n-butyl alpha-cyanoacrylate tissue adhesive. II.", Surgery, 1968 March, 63(3), 481-9). For this reason, cyanoacrylates have not found favor with the FDA for internal tissue closure. Only topical skin closure applications have been FDA approved.
Other disadvantages of cyanoacrylate tissue adhesives are their runniness (low viscosity) in uncured form and stiffness when cured.